Construction d'Orthogonaux dans les Groupes abéliens finis eet confusions d'effets dans les plans factoriels

This paper is devoted to factorial designs generated by Patterson's (1976) DSIGN method. As stated by Bailey (1977), the identification of confounded effects may be done here by constructing annihilators of given subgroups of the treatment group.     

Sur le carré d'un opérateur non linéaire

Sans résumé     

Energy levels in the nucleus 156Dy through the 159Tb(p, 4nγ)156Dy reaction

Using the ¹⁵⁹Tb(p, 4nγ)¹⁵⁶Dy reaction at E_p = 27 to 51 MeV and standard on-line γ-ray spectroscopy methods, the energies and decay properties of members of various rotational bands in the nucleus ¹⁵⁶Dy have been investigated, i.e. the ground-state band up to 14_g⁺, the β-vibrational band up to 14_β⁺,the γ-vibrational band up to 11_γ⁺,and two other bands, one with odd-spin levels up to 11, the other with even-spin levels up to 10. The results are compared with various calculations in the framework of the collective model, and no satisfactory fit is obtained; possible improvements of the model to remove these discrepancies are suggested.     

Superconductivity of the graphite intercalation compounds KHgC8 and RbHgC8

Superconductivity was observed in the graphite intercalation compounds, KHgC₈ and RbHgC₈, using an AC induction technique. The transition temperatures were 1.90K and 1.44K for KHgC₈ and RbHgC₈ respectively. A full Meissner effect was observed for KHgC₈ with a temperature dependant anisotropy in critical field with a value of 25 ± 5 at T_c.     

A thermometric study of the dissolution of copper in acid solutions

The dissolution of Cu in solutions of HNO₃ of different concentrations has been studied by the thermometric method. Starting from the initial temperature, T_i, the temperature—time curves exhibit an induction period followed by a rapid rise in temperature to a maximum value, T_m, attained t min after the start of the reaction. T_m increases and t decreases with increase of the acid concentration, M. ΔT (i.e.T_m ? T_i) and the reaction number (R.N. = (T_m ? T_i)/t) vary with M according to: ΔT = k(M ? M₀) and R.N. = A₁Mⁿ, where k, M₀, A₁ and n are constants.The effect of varying concentrations of HCl, H₂SO₄ and H₃PO₄ on the R.N. of Cu in 3.5 M HNO₃ was examined. Small amounts of these acids lower the R.N. (inhibition) due to the displacement of an active species on the surface of the metal by the anion of the acid. Larger additions of the acids accelerate dissolution. The concentration at which the added acid changes from corrosion-inhibitor to accelerator varies as HCl < H₂SO₄ < H₃PO₄. This sequence is considered to parallel the strength of adsorption of the respective anions. The results of experiments with salt additions confirm this view; all salts act only as dissolution-retardants. Calculations pertaining to the effect of the various ions on the R.N. support the conclusion that the dissolution of Cu in HNO₃ is autocatalytic in nature, and depends on the [H⁺]/[NO₃^?] ratio.Cu does not dissolve in air-free, cold HCl. Attack takes place, however, in the presence of KNO₃. Under these conditions attack is of the pitting- rather than the general type. The temperature rises suddenly after an incubation period, which decreases in length with increase of the amount of the added salt.Proof of the involvement of HNO₂ in the autocatalytic cycle of Cu dissolution in HNO₃ is obtained from the results of urea additions to the solution.     

Hindered rotation and electronic distribution in thiocarbamates

We wish to report here the isolation of methyl N-(p-methoxybenzyl)thiocarbamate, a natural product extracted from Pentadiplandra brazzena Bailli, and the synthesis of its homologue, benzyl N-(2-phenylethyl)thiocarbamate. The barrier to internal rotation calculated from a complete lineshape analysis of the temperature dependent ¹H n.m.r. spectra is discussed. The extent of delocalization on the three N, S and O substituents on the central trigonal carbon atom is gauged from a double labelling experiment.     

Kinetics of the autocatalytic oxidation of N-amino-3-azabicyclo[3,3,0]octane by chloramine in aqueous medium

The kinetics of the degradation of N-amino-3-azabicyclo[3,3,0]octane by chloramine has been studied by GC and HPLC in stoichiometric conditions in a solution buffered with NaOH/KH₂PO₄ and Na₂B₄O₇.10 H₂O between pH = 10.5 and 13.5. The second-order reaction exhibits specific acid catalysis which indicates competitive oxidation between the haloamine and the neutral and ionic forms of the bicyclic hydrazine. The enthalpy and entropy of activation were determined at pH = 12.89. In a nonbuffered solution, the interaction is autocatalyzed due to acidification of the mixture by the ammonium ions. In basic medium, the reaction forms an endocyclic hydrazone. A mathematical treatment based on an implicit equation allows a quantitative interpretation of all the phenomena observed over the above pH interval. This takes both the acid/base dissociation equilibria and the alkaline hydrolysis of the chloro-derivative into account. © 1995 John Wiley & Sons, Inc.     

A digital scanning Auger electron microscope

A new instrument, a scanning Auger microscope with digital scanning and a concentric hemispherical analyser, is described together with some preliminary demonstration results. The sample, a titanium ribbon, was hand polished and resistively heated. After a short heating to remove some of the overlay carbon and oxygen, the sample showed some irregular areas of very low SEM contrast which were attributed to calcium from the L_{2, 3}VV Auger process at 288 eV. Using this calcium peak a scanning Auger map of the areas showed high contrast and the corresponding titanium Auger maps demonstrate that this indeed was an overlayer of calcium. The probe resolution was 50 nm and a single picture was produced in 3 min.     

Die optischen Konstanten des Kaliums im Wellenlängenbereich von 3650 bis 20000 Å

The optical constantsn andk of the alkali metal potassium have been measured in the wavelength region from 0·365μ to 2μ, in the solid and liquid state at temperatures between ?180° C and +85° C by the usual method of analysing intensity and polarisation of the monochromatic radiations reflected by the metals surface. The mirrorlike surfaces, free of any contamination and not distorted by any treatment, were prepared and measured in ultrahigh vacuum, the metal being purified before by careful repeated destinations in high vacuum. Values thus obtained forn, k, k ²?n ² and 2nk are listed in tables 1 and 2. Discussion of these values especially with regard to the Drude-theory of optical constants of metals is given in two subsequent communications.